[en] Most of the genetic effects induced by chemicals have their counterpart in the genetic effects induced by radiations. Also it is at the genetic level where mutagenic effects are expressed in human populations. Therefore, radiation dosimetry can be used as a standard for comparison if comparisons are made on one genetic parameter at a time. Comparative dosimetry will have to be made precise. Mutagenic efficiency, mutagenic effectiveness, species and dose-action kinetics will have to be taken into account for each compound tested. (author)
Source
International Atomic Energy Agency, Vienna (Austria); Panel proceedings series; p. 5-10; ISBN 92-0-111180-0; 
; 1980; p. 5-10; IAEA; Vienna; Advisory group meeting on radiobiological equivalents of chemical pollutants; Vienna, Austria; 12 - 16 Dec 1977; IAEA-AG--97/2
; 1980; p. 5-10; IAEA; Vienna; Advisory group meeting on radiobiological equivalents of chemical pollutants; Vienna, Austria; 12 - 16 Dec 1977; IAEA-AG--97/2
[en] As a first-order or second-order mutagenic or carcinogenic event arises from a spontaneous background, the first increases in frequency with dose appear superficially as partial-hit or partial-target kinetic events. This appearance dose not necessarily reflect reality, for when one subtracts the spontaneous mutation frequency at each dose point, the first- or second-order dose-effect relation still obtains, continuing even below the spontaneous mutation level. On the other hand, even taking into consideration spontaneous events, partial-target mutagenic and carcinogenic dose-effect kinetics have been observed at low doses of ionizing radiation. The partial-target events can be explained by assuming (1) that mixtures of cells of different sensitivity are in the target population; (2) that energy must be absorbed in two or more closely involved cells for the event to take place; or (3) that cumulative damage is taking place in repair systems. (author)
Source
International Atomic Energy Agency, Vienna (Austria); World Health Organization, Geneva (Switzerland); Proceedings series; v. 1 p. 361-368; ISBN 92-0-010076-7; ; 1976; IAEA; Vienna; Symposium on biological effects of low-level radiation pertinent to protection of man and his environment; Chicago, Ill., USA; 3 Nov 1975; IAEA-SM--202/511
; 1976; IAEA; Vienna; Symposium on biological effects of low-level radiation pertinent to protection of man and his environment; Chicago, Ill., USA; 3 Nov 1975; IAEA-SM--202/511
[en] The concept of channelling of lesions in DNA into defined repair systems has been used to explain many aspects of induced and spontaneous mutation. The channelling hypothesis states that lesions excluded from one repair process will be taken up by another repair process. This is a simplification. The three known modes of repair of damage induced by radiation are not equivalent modes of repair; they are, instead, different solutions to the problem of replacement of damaged molecules with new molecules which have the same informational content as those that were damaged. The mode of repair that is used is the result of the response to the situation in which the damage takes place. Thus, when the most likely mode of repair does not take place, then the situation changes with respect to the repair of the lesion; the lesion may enter the replication fork and be reparable by another route
Journal
[en] Radiations and chemical mutagens kill cells in numerous ways: by one of several kinds of induced dominant lethality, by a direct inactivation of function as with sperm, and by genetically undefinable types of death which may or may not be related to dominant lethality per se. Also, chemical mutagens appear to exert a curious enhancement of the fertilizing capacity of sperm. The different stages of oflgenesis and spermatogenesis respond with unequal sensitivity to radiation, and individual cells pass through stages conferring as much as a 50-fold difference in sensitivity. Where species of Diptera, Hymenoptera and Coleoptera can be compared, a striking similarity of response to radiation can be observed, both to stage sensitivity and degree of response with dose. The silkworm, Bombyx mori (Lepidoptera), seems to be similar in most respects to representatives of the other orders in response of germ cells to radiation, but differs sharply in types of dominant lethality induced. Species having atypical genetic mechanisms (e.g.,the lecanoid system of Planococcus citri (Hemipt. : Coccidae) are special cases, and their responses to radiation are considerably modified from those of other species. For insect population control by the irradiation-of-male method, dominant lethality is as advantageous in species where matings are multiple as in species where mating occurs once. Sperm inactivation and gonial killing can be regarded as instances of true sterility and are maximally effective only in species where mating occurs once. For most efficient control, doses should be chosen which would induce maximum dominant lethality, minimum sperm inactivation and complete killing of gonial cells. These parameters are simple to determine by gamete viability measurements, irradiated and unirradiated population competition experiments and histological examination of gonia. (author)
[fr]
Les rayonnements et les agents chimiques de mutation detruisent les cellules de nombreuses facons: par l'un des modes d'induction d'une letalite dominante, par l'inactivation directe d'une fonction et par des manieres genetiquement indefinissable, liees ou non a la letalite dominante. Les agents chimiques de mutation paraissent egalement provoquer un accroissement curieux du pouvoir fertilisant du sperme. La radiosensibilite varie avec les divers stades de l'oogenese et de la spermatogenese; certaines cellules passent par des stades au cours desquels leur radiosensibilite peut varier dans un rapport de 1 a 50. Des comparaisons entre des diptetes, des hymenopteres et des coleopteres ont revele une similarite frappante dans la maniere dont ces especes reagissent aux rayonnements, tant en ce qui concerne la sensibilite aux divers stades de developpement que l'intensite de la reaction en fonction de la dose. Le ver a soie Bombyx mori (lepidoptere) semble avoir beaucoup de points communs avec les representants des autres ordres en ce qui concerne l'effet des rayonnements sur les cellules germinales, mais il en differe nettement pour ce qui est des facteurs letaux dominants induits. Les especes presentant des mecanismes genetiques anormaux (par exemple, le Planococcus citri, coccide hemiptere) constituent des cas particuliers et ils reagissent aux rayonnements de facon tres differente des autres especes. Dans la lutte contre les insectes par la methode de Tirradiation des males, la letalite dominante est aussi efficace pour les especes ou l'accouplement a lieu plusieurs fois que pour celles ou il a lieu une seule fois. On peut considerer l'inactivation du sperme et la destruction des cellules des gonades comme des facteurs de sterilite reelle; leur efficacite est maximum chez les especes ou l'accouplement n'a lieu qu'une seule fois. Pour le controle le plus efficace, il faudrait avoir recours a des doses provoquant la letalite dominante maximum, l'inactivation minimum du sperme et la destruction totale des cellules des gonades. Il est facile de determiner ces parametres en calculant la viabilite des gametes, au moyen d'experiences comparatives avec des populations non irradiees ainsi que par l'examen histologique des gonades. (author)[es]
Las radiaciones y los productos quimicos mutagenos pueden matar las celulas de modos diversos, a saber: mediante la induccion de uno o varios tipos de elementos letales dominantes, por inactivacion directa de una funcion, como la produccion de esperma, y por procedimientos geneticamente indefinibles de exterminacion que pueden o no estar relacionados con la letalidad dominante intrinseca. Por otra parte, los productos quimicos mutagenos parecen provocar un curioso aumento de la capacidad fertilizante de la esperma. La radiosensibilidad varia segun las diferentes etapas de la oogenesis y de la espermatogenesis, y las celulas pasan por fases en que dicha sensibilidad llega a ser 50 veces superior o inferior que en otras. En la medida en que distintas especies de dipteros, himenopteros y coleopteros son comparables, puede observarse una sorprendente analogia en la radiosensibilidad, tanto segun las etapas como segun las dosis. La radiosensibilidad de las celulas germinales del gusano de seda Bombyx mori (Lepidopt. ) parece similar en muchos aspectos a la de los insectos de otros ordenes, pero en cambio hay grandes diferencias en cuanto a los tipos de elementos letales dominantes que en el pueden inducirse. Las especies con mecanismos geneticos atipicos (por ejemplo, el sistema lecanoideo del Planococcus citri (Hemipt. ; Coccidae) constituyen casos especiales y su radiosensibilidad varia considerablemente en relacion con la de otras especies. Para la lucha contra los insectos por el metodo de irradiacion de los machos, la creacion de un elemento letal dominante ofrece en las especies donde las copulas son multiples las mismas ventajas que en las especies que copulan solo iva vez. La inactivacion de la esperma y la exterminacion de las celulas gonadicas pueden considerarse como casos de autentica esterilizacion que alcanzan su maxima eficacia solo en las especies que copulan una vez. Para que la lucha contra los insectos sea eficaz hay que aplicar dosis que produzcan un factor letal dominante maximo, una inactivacion minima de la esperma y una exterminacion completa de las celulas gonadicas. Estos parametros se pueden determinar facilmente con la medicion de la viabilidad de los gametos, los experimentos con poblaciones irradiadas y no irradiadas y el examen histologico de las gonias. (author)[ru]
Izlucheniya i khimicheskie mutagennye veshchestva umershchvlyayut kletki razlichnymi putyami:odnim iz vidov obrazovaniya dominantnykh letalej, neposredstvennoj inaktivatsiej funktsii, kak, naprimer, v otnoshenii spermy, i geneticheski neopredelimymi vidami smerti, kotorye mogut byt' svyazany ili ne svyazany s dominantnoj letal'nost'yu. Khimicheskie mutageny proizvodyat, po-vidimomu, neobychajnoe usilenie oplodotvoryaptsej sposobnosti spermy. Razlichnye stadii oogeneza i spermatogeneza reagiruyut s neodinakovoj chuvstvitel'nost'yu na obluchenie, i raznitsa v chuvstvitel'nosti otdel'nykh kletok na nekotorykh stadiyakh razvitiya dostigaet 50 raz. Razlichnye stadii oogeneza i spermatogeneza reagiruyut s neodinakovoj chuvstvitel'nost'yu na obluchenie, i raznitsa v chuvstvitel'nosti otdel'nykh kletok na nekotorykh stadiyakh razvitiya dostigaet 50 raz. Tam, gde predstavlyaetsya vozmozhnym sravnivat' dvukrylykh, pereponchatokrylykh i zhestkokrylykh nasekomykh, mozhno nablyudat' zamechatel'noe edinoobrazie reaktsii ka obluchenie kak po urovnyu radiochuvstvitel'nosti na opredelennoj stadii, tak i po zavisimosti stepeni reaktsii ot dozy. Shelkopryad, Bombyx mori (otryad cheshuekrylykh), predstavlyaetsya pokhozhim v bol'shinstve otnoshenij na predstavitelej drugikh otryadov po reaktsii polovykh kletok na radiatsiyu, no rezko otlichaetsya po tipam indutsirovannykh dominantnykh letalej. Vidy s atipichnym geneticheskim mekhanizmom (naprimer, lekanoidnaya sistema Planococcus citri (otryad nastoyashchikh poluzhestkokrylykh Coccldae)) predstavlyayut soboyu osobye sluchai, i ikh reaktsiya na obluchenie znachitel'no otlichaetsya ot reaktsii nasekomykh drugikh vidov. Pri istreblenii populyatsij nasekomykh oblucheniem samtsov dominantnaya detal'nost' predstavlyaetsya stol' zhe perspektivnoj dlya vidov s odnokratnym sparivaniem, kak i dlya vidov s mnogokratnym sparivaniem. Inaktivatsiyu spermy i umershchvlenie polovykh kletok mozhno schitat' primerami polucheniya istinnoj steril'nosti, naibolee ehffektnoj dlya vidov, gde sparivanie proiskhodit odnokratn'. Dlya naibolee ehffektivnogo istrebleniya dolzhny vybirat'sya takie dozy, kotorye vedut k polucheniyu maksimal'noj dominantnoj letal'nosti, proizvodyat minimal'nuyu inaktivatsiyu spermy i vyzyvayut polnoe umershchvlenie polovykh kletok. Ehti parametry legko poddayutsya opredeleniyu posredstvom izmereniya zhiznesposobnosti gamet, ehksperimentami s konkurentsiej mezhdu obluchennymi i neobluchennymi populyatsiyami, a takzhe gistologicheskim issledovaniem gonad. (author)Source
International Atomic Energy Agency, Vienna (Austria); Food and Agriculture Organization of the United Nations, Rome (Italy); 526 p; Sep 1963; p. 367-385; Symposium on the Use and Application of Radioisotopes and Radiation in the Control of Plant and Animal Insect Pests; Athens (Greece); 22-26 Apr 1963; ISSN 0074-1884; ; 13 figs., 2 tabs., 57 refs.
; 13 figs., 2 tabs., 57 refs.
[en] Mice can survive lethal doses of ionizing radiation if deoxyribonucleosides or 'highly polymerized' salmon sperm DNA (Sigma) are administered 30 min to 24 h post-irradiation. DNA is more effective than deoxyribonucleosides in increasing the survival frequency. At supralethal exposures of γ-irradiation, deoxyribonucleosides and DNA are equally effective in reversing radiation damage which otherwise leads to chromosome breakage. The micronucleus frequencies in the polychromatic erythrocytes of bone marrow cells from DNA- or deoxyribonucleoside-treated mice were near the unirradiated control values. This reduction in chromosome breakage was = 4-fold when compared with the irradiated, saline-treated control. 'Highly polymerized' DNA protects against mortality if administered 48 and 24 h prior to irradiation. This is somewhat comparable to the effectiveness of the growth factors Interleukin-1α (IL-1α) or tumor necrosis factor-α (TNFα) administered prior to irradiation. With survival as criterion, the sensitivity of 4 lines of mice to γ-irradiation is BALB/c>C3H/OuJ≥C3H/HeJ>C57B1/6
Journal
[en] The amount of radiation required to double the frequency of mutations or tumours over the rate of those that occur spontaneously is called the rate-doubling dose. An equivalent concept has been proposed for exposure to other environmental mutagens. The doubling dose concept is predicated on the assumption that all human populations have the same spontaneous mutation rate, and that this spontaneous mutation rate is known. It is now established for prokaryotes and lower eukaryotes that numerous genes control the spontaneous mutation rate, and it is likely that the same is true for human cells as well. Given that the accepted mode of evolution of human populatons is from small, isolated groups of individuals, it seems likely that each population would have a different spontaneous mutation rate. Given that a minimum of twenty genes control or affect the spontaneous mutation rate, and that each of these in turn is susceptible to spontaneously arising or environmentally induced mutations, it seems likely that every individual within a population (except for siblings from identical multiple births) will have a unique spontaneous mutation rate. If each individual in a population does have a different spontaneous mutation rate, the doubling dose concept, in rigorous terms, is fallacious. Therefore, as with other concepts of risk evaluation, the doubling dose concept is subject to criticism. Nevertheless, until we know individual spontaneous mutation rates with precision, and can evaluate risks based on this information, the doubling dose concept has a heuristic value and is needed for practical assessment of risks for defined populations. (author)
Source
International Atomic Energy Agency, Vienna (Austria); Proceedings series; v. 2 p. 277-290; ISBN 92-0-010778-8; ; 1978; v. 2 p. 277-290; IAEA; Vienna; Symposium on the late biological effects of ionizing radiation; Vienna, Austria; 13 - 17 Mar 1978; IAEA-SM--224/402; 33 refs.
; 1978; v. 2 p. 277-290; IAEA; Vienna; Symposium on the late biological effects of ionizing radiation; Vienna, Austria; 13 - 17 Mar 1978; IAEA-SM--224/402; 33 refs.